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Banana wilt diseases are among the most important banana production constraints worldwide. The narrow genetic diversity of cultivated bananas, coupled with the high variability of pathogens, has led to decimation of susceptible cultivars. Strict quarantine measures to exclude pathogens from disease-free areas and the use of resistant cultivars in already affected areas are the most effective control practices. Significant research efforts have been directed towards breeding additional resistant hybrids. Current research strategies for management of banana wilts have explored use of conventional breeding, somaclonal variation and genetic engineering. This review describes the recent spread, economic losses, management strategies and future research directions of the major banana wilts. [ABSTRACT FROM AUTHOR]

Banana (Musa spp.), an important staple food in the tropical and subtropical regions, is highly susceptible to drought. Developing drought-tolerant bananas using available germplasm offers a long-term solution to mitigate drought effects. The East and Central Africa Banana Germplasm Collection in Uganda contains genetically diverse genotypes whose potential for drought tolerance breeding is yet to be established. This study aimed to determine the response of 14 Musa spp. genotypes to drought stress using phenotypic and physiological traits in order to select promising genotypes for use in breeding. Two genotypes with a known reaction to water deficit conditions were included as local checks. Three-month-old tissue culture-derived plantlets were completely deprived of water for four weeks while control plants were regularly irrigated back to field capacity, and both sets maintained under screen-house conditions. Drought stress resulted in significant reductions in plant height, total leaf area, number of leaf cigars and functional leaves, total dry matter, chlorophyll and relative water content. Water use efficiency (WUE) of 12 genotypes increased under stress conditions. Stomatal conductance was affected by the genotype-porometer reading time interaction. Genotype "ITC.0987" was the most tolerant, considering that moisture stress had the least effect on its above-ground growth. Among the improved diploids, "TMB2x9722-1" had the least total dry matter reduction and highest WUE, while "TMB2x9172" showed the least decrease in relative water content and highest root-shoot ratio increase under stress. Thus, "ITC.0987", "TMB2x9722-1" and "TMB2x9172" are essential drought-tolerant candidates that may be utilized in breeding. [ABSTRACT FROM AUTHOR]

Eco-friendly pest control options are highly needed in food crop production systems to mitigate the hazards of synthetic chemical pesticides. Entomopathogenic fungal biopesticides—Metarhizium anisopliae strains ICIPE 20 (oil-formulation containing 1.0 × 109 conidia/mL) and ICIPE 69 (commercialized biopesticide known as Mazao Campaign®)—were evaluated against Tuta absoluta on tomato through inundative foliar spray and compared with the commonly used pesticide Dudu Acelamectin 5% EC (Abamectin 20 g/L + Acetamiprid 3%) and untreated plot. All the treatments were arranged in a randomized complete block design with three replicates. The field experiments were conducted for two consecutive cropping seasons in Mukono district, Uganda. Tuta absoluta infestation, injury severity on leaves and fruits, fruit yield loss, marketable fruit yield gain and cost–benefit ratio of the treatments were assessed. The results during both seasons showed a significant lower fruit yield loss in M. anisopliae ICIPE 20-treated plots compared to untreated plots, with a marketable fruit yield gain exceeding 22% and a cost–benefit ratio greater than 2.8 (BCR~3). Dudu Acelamectin 5% EC outperformed all the other treatments, but needs to be considered with caution due to its non-target effect and resistance development, whereas M. anisopliae ICIPE 69 performed the least well. In addition, the findings showed the high degree of efficacy and economic viability of these biopesticides as a potential T. absoluta control option in the field. However, it is important to further explore different formulations of these eco-friendly biopesticides, inoculum delivery approach, application frequency, their effectiveness in different agro-ecological zones and compatibility with commonly used pesticides in tomato production systems for sustainable management of T. absoluta. [ABSTRACT FROM AUTHOR]

Phytopathogenic bacteria are economically important because they affect crop yields and threaten the livelihoods of farmers worldwide. The genus Xanthomonas is particularly significant because it is associated with some plant diseases that cause tremendous loss in yields of globally essential crops. Current management practices are ineffective, unsustainable and harmful to natural ecosystems. Bacteriophage (phage) biocontrol for plant disease management has been of particular interest from the early nineteenth century to date. Xanthomonas phage research for plant disease management continues to demonstrate promising results under laboratory and field conditions. AgriPhage has developed phage products for the control of Xanthomonas campestris pv. vesicatoria and Xanthomonas citri subsp. citri. These are causative agents for tomato, pepper spot and speck disease as well as citrus canker disease. Phage-mediated biocontrol is becoming a viable option because phages occur naturally and are safe for disease control and management. Thorough knowledge of biological characteristics of Xanthomonas phages is vital for developing effective biocontrol products. This review covers Xanthomonas phage research highlighting aspects of their ecology, biology and biocontrol applications. [ABSTRACT FROM AUTHOR]

An optimal control framework is designed in which the use of clean planting materials, debudding, disinfection of tools, and roguing are considered as control measures of Banana Xanthomonas Wilt (BXW) within a plantation of multiple cultivars. A model for a special case of two cultivars (AAA- and ABB-genome cultivars) was analyzed. By Pontryagin’s Maximum Principle, we characterized and discussed possible control strategies that substantially reduce the infection levels of BXW within a plantation of ABB- and AAA-genome cultivars. A combination of both prevention and containment controls yielded the greatest decline in the infection levels in both cultivars. Additionally, for effective BXW management, it is important to assess the endemic level of the plantation before application of controls, and once implemented, this should be maintained even when the disease is undetectable to eliminate possible resurgence. [ABSTRACT FROM AUTHOR]

Xanthomonas wilt, caused by Xanthomonas campestris pv. musacearum has, since 2001, become the most important and widespread disease of Musa in East and Central Africa. Over the past decade, new research findings and especially feedback from small-scale farmers have helped in fine-tuning Xanthomonas wilt control options. During the initial years of the Xanthomonas wilt epidemic in East Africa, the complete uprooting of diseased mats and the burning or burying of plant debris was advocated as part of a control package which included the use of clean garden tools and early removal of male buds to prevent insect vector transmission. Uprooting a complete mat (i.e. the mother plant and a varying number of lateral shoots) is understandably time-consuming and labour intensive and becomes very cumbersome when a large number of diseased mats have to be removed. Recent research findings suggest that Xcm bacteria do not colonize all lateral shoots (i.e. incomplete systemicity occurs) and even when present that this does not necessarily lead to symptom expression and disease. This led to a new control method whereby only the visibly diseased plants within a mat are cut at soil level. The underlying idea is that the continued removal of only the diseased plants in a field will reduce the inoculum level and will bring down disease incidence to an acceptable level. This method is less labour intensive and takes a short time compared to the removal of a complete mat. However, single diseased stem removal needs to go hand in hand with prevention of new infections that can occur through the use of contaminated garden tools or through insect vector transmission. Novel transgenic approaches are also discussed. This paper presents an overview of past and ongoing research towards the development of a more practical and less demanding control strategy for Xanthomonas wilt. [ABSTRACT FROM AUTHOR]

Attraction of adult banana weevil, Cosmopolites sordidus to volatiles from banana pseudostem tissue and the synthetic pheromone Cosmolure+ presented singly or in combination, was studied in the laboratory and in the field. Olfactometric studies in the laboratory showed that 50 g of fermented banana pseudostem tissue was as attractive as pheromone but more attractive than 50 g of fresh pseudostem tissue. In the laboratory, volatiles from pseudostem tissue had an additive effect on attraction of weevils to the pheromone but the effect was not significant in the field. Field trials, however, showed that attractiveness to weevils was positively correlated with the amount of fermented tissue added to the pheromone. The results indicate that fresh or fermented pseudostem tissue may enhance pheromone trap catches but the effect was not large enough to warrant their deployment for the optimisation of the infochemical-based trapping system for the management of C. sordidus. [ABSTRACT FROM AUTHOR]

Candidate strains of Beauveria bassiana were identified for use in integrated pest management of the banana weevil Cosmopolites sordidus. Horizontal field transmission of B. bassiana between banana weevils using different delivery systems, including aggregation pheromones, was investigated. We observed that infected weevils could transmit the fungal pathogen to healthy individuals. Most dead weevils (52%) due to B. bassiana infection were found at the base of banana plants in the leaf sheath or in the soil near banana plants. Significantly more weevils died from the pathogen in plots where B. bassiana was applied in combination with the pheromone than where it was applied alone. Our data demonstrate that C. sordidus aggregation pheromone can be a valuable tool to enhance the dissemination of B. bassiana for the control of C. sordidus. [ABSTRACT FROM AUTHOR]

Studies were conducted in Uganda to evaluate the influence of distance, environmental factors, trap location and trap type on catches of Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae) in pheromone-baited traps. Marked weevils were released at recorded locations within plots. Trap efficiency was low and decreased with distance from the pheromone trap. When weevils were released in close vicinity to the trap, significantly more weevils were recaptured from 0.5 m compared to those recaptured from 4 m within 30 days of trap placement. Relative humidity showed a significant positive relationship to C. sordidus catches, while wind speed, temperature and rainfall had no effect. Covering pheromone-baited traps with banana leaves increased capture rates. In one experiment, more weevils were captured in pheromone-baited traps placed in alleys than at the base of mats, while no differences were found in the second. This study provides information on how various factors influence the effectiveness of pheromone-baited traps that will assist in designing a pheromone-based mass trapping strategy for the control of C. sordidus . [ABSTRACT FROM AUTHOR]

Three different bioassay methods to investigate the orientation behaviour of the banana weevil, Cosmopolites sordidus (Germar) (Coleoptera: Curculionidae), to host plant volatiles and a synthetic pheromone (cosmolure+) were compared. A locomotion compensator was used to separately record walking tracks in response to three odour sources. The data show that C. sordidus uses odourconditioned anemotaxis in its orientation to the odour sources tested. Of the two olfactometers tested, a dual port olfactometer using a continuous airflow showed stronger discrimination by C. sordidus to the different odours compared with a double pitfall olfactometer. The results of all three bioassays indicate that C. sordidus responds in an additive way to the combination of fermentation plant volatiles and the synthetic pheromone. [ABSTRACT FROM AUTHOR]

Banana Xanthomonas Wilt (BXW) is an important emerging and non-curable infectious plant pathogen in sub-Saharan Africa that can cause up to 100% yield loss, negatively impacting sustainable access to food and income to more than 100 million banana farmers. This study disentangles adopters into partial and full adopters to investigate the factors that are relevant to sustain the adoption process of BXW control practices and quantifies the impact of adopting the practices. Data from a randomly selected sample of 1200 banana farmers in Uganda where the disease is endemic was used. A multinomial logit model was used to determine the factors affecting adoption of control practices and augmented inverse probability weighting was employed to estimate the impacts of adoption on banana productivity and sales. Results show that training a woman farmer and having diverse sources of information about BXW control practices increased adoption of the control practices and reduced the disease incidences. Farmers who adopted all the recommended control practices achieved significantly the highest values of banana production and sales. We conclude that improving information access through farmers' preferred communication channels, having women-inclusive trainings, and a combination of cultural practices are effective ways for sustaining adoption of the control practices. [ABSTRACT FROM AUTHOR]